Steam-engine slide-valve.



J. 0. LONGAN.

STEAM ENGINE SLIDE VALVE.

APPLICATION FILE-D AUG 5, 1913.

1,1 17,070. I Patented Nov. 10, 1914.

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awuzuto'c HE NORRIS PETERS CO. PHOTO-LITHQ. WASHINGTON D. C.

UNITED STATES. f grnivr OFFICE.

7 JOHN OSBORNE LONGAN, or MCGEE, SASKATCHEWAN, cANADA.

STEAM-ENGINE SLIDE-VALVE.

To all whom it may concern:

Be it known that-I, JOHN OsBonNn LON- GAN, a citizen of Canada, residing at McGee, in the Province of Saskatchewan and Dominion of Canada, have invented new and useful Improvements in Steam-Engine Slide- Valves, of which the following is a specification.

This invention relates to improvements in steam engine slide valves and has particular application to balanced slide valves.

In carrying out the presentinvention, it is my purpose to provide a double ported balanced slide valve which will control the admission and exhaust of the steam to and from the cylinder with least stroke and whereby friction between the parts will be minimized.

It isalso my purpose to provide. a slide valve for steam engines which will be constructed in such manner that back pressure on the valve will be eliminated and the steam fed to the engine cylinder from both ends of the valve chest whereby the pressure of the live steam within the chest at the opposite sides of the valve will be balanced.

\Vith the above and other objects in view,

the invention consists in the construction, combination and arrangement of parts hereinafter set forth in and falling within the scope of the claim.

In the accompanying drawing, Figure 1 is a fragmentary longitudinal sectional view through a steam engine cylinder equipped with a valve constructed in accordance with the present invention. Fig. 2 is a transverse sectional view through the same.

Referring now to the accompanying drawing in detail, the numeral 1 designates a portion of the steam chest of an engine,.

such chest having the usual steam ports 2 and 3 and an exhaust port 4:.

The numeral 5 designates a slide valve mounted within the steam chest and controlling the flow of steam from the chest through the passages 2 and 3 to the respective ends of the engine cylinder and having formed in the under face thereof an exhaust cavity 6 adapted to establish communication between the exhaust passage 1 and the exhaust side of the cylinder by way of one or the other of the passages 2, 3, as is readily understood by those skilled in the art.

Formed in the valve 5 around the exhaust cavity 6 therein is a steam passage 7 opening steam chest.

Specification of Letters Patent. Patgnted N 10, 1914.

Application filed August 5, 1913. Serial No. 783,107.

onto the lower face of the valve adjacent to the opposite ends thereof and adapted to establish communication between one or the other of the inlet passages 2, 3 and the op 130-.

site end of the steam chest when such passage is taking steam. For instance, when the valve is in the position illustrated in Fig. 1, the passage 2 will be taking steam from the adjacent end of the steam chest into the respective end of the cylinder to drive the piston in one direction, while the exhaust cavity 6 will have established communication between the passage 3 and the exhaust passage t so that the spent steam on the exhaust side of the piston will be discharged to the atmosphere. Simultaneously with the flow of steam from the respective end of the steam chest into the passage 2, the

steam from the opposite side of the chest flows through the passage 7 around the exhaust cavity in the valve and into the passage 2, thereby enabling a relatively large volume of-steam to flow into the cylinder with a given movement of the valve.

In order to eliminate pressure on thetop of the valve, I employ a cover 8 which, in-

the present instance, is of inverted U-shape side edges of the valve, the lower extremities of the limbs of such U-shaped cover resting upon and being suitably secured to the lower wall of the valve chest at the opposite sides of the seat of the slide valve. Interposed between the top surface of the valve 5 and the lower surface of the interconnecting member of, the cover 8 is what may be termed a release plate 9 of a length approximately equal to that of the valve and held in frictional contact with the respective surface of the valve by means of a coiled expansion spring 10 arranged within an aperture in the upper member of the valve cover and having one end bearing upon the release plate and the opposite end abutting the inner face of the cover of the Suitable bolts 11 are passed through the upper member of the valve cover and engage openings in the release plate so as to hold the latter against movement relatively to the cover, while set screws 12, 12 are passed through the cover of the valve chest and bear upon the valve cover to hold the latter secure.

From the foregoingfldescription taken in connection with the accompanying drawing, the construction and mode of operation of in cross section and envelops the top and my improved double ported slide valve will be readily apparent.

In practice, the valve slides in a direction opposite from the movement of the piston, as is Well understood, since steam is admitted to the steam end of the cylinder around the exhaust cavity. This method of admitting steam increases the area of the passage Way for the ingress of steam to the cylinder and when the valve leaves its seat the release plate takes care of the same and facilitates reseating. This plate eliminates the use of valve rings, packing and the like and as there is more or less steam between the valve and the release plate when the former is on the seat, less friction is set up between the parts.

I claim:

In combination, a steam chest provided With steam passages adapted to establish communication between the chest and the engine cylinder and an exhaust passage leading from the chest to the atmosphere, a slide valve Within said chest and controlling said steam passages, a substantially U shaped cover Within said chest enveloping the top and sides of the valve whereby pressure on the upper side of the valve is avoided, a release plate interposed between the upper surface of said valve and the adjacent face of said cover, means connecting said release plate and cOver to prevent sliding movement of the former, and a spring acting upon the upper surface of said plate and holding the latter in frictional engagement With the up per surface of the valve.

In testimony whereof I afiix my signature in presence of two Witnesses.

JOHN OSBORNE LONGAN. Witnesses A. M. lVILsoN, lVM. E. MonRIsoN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Eatents, Washington, D. G. 

